Prior U.S. Pat. Nos. 3,721,069, 4,184,858, 4,724,807, 5,140,957, and 5,479,907 relate to air-oil separators used in conjunction with internal combustion engines. The specifications and claims of these patents are incorporated herein by reference. The air-oil separators disclosed in these patents comprise mechanical means disposed therein for mechanically separating oil from an air-oil mixture routed thereto from an engine crankcase. More specifically, such air-oil separators include one or more baffle and/or filter material for effecting such oil separation. The separated oil component is removed from the separator for either further treatment or for routing back to an engine crankcase.
Increasingly stringent environmental regulations, and a heightened consciousness of environmental conservation, has mandated cleaner operation of hydrocarbon powered sources such as automobiles, boats, trucks, motorcycles, or the like. As a result, blow-by devices such as pollution control valves have become required standard equipment for all automobiles. These blow-by devices capture air-oil emissions from the crankcase of a hydrocarbon burning internal combustion engine and communicate them in a closed system to the air intake system for combustion. The emissions generated from the crankcase of diesel engines, for example, are heavily ladened with oil and other heavy hydrocarbons. Accordingly, air-oil separators such as those previously described have been developed in an effort to make the operation of such engines cleaner and more efficient. Such devices have been developed to both silence and filter inlet air routed to an intake of an engine, separate oil and other hydrocarbons emitted from a contaminated engine atmosphere, and regulate the pressure within an engine crankcase.
The '957 and '907 patents each discloses an air-oil separator system comprising a combined air-filter/air-oil separator device that incorporates a particular arrangement of baffles, filtration material, and/or arrangement of airflow passages therethrough to remove oil from an air-oil mixtures passing therethrough from an engine crankcase. Each such system also includes a vacuum limiter that is external from the separator device and that is connected in-line between the separator device and the engine crankcase to limit the amount of vacuum that is drawn on the crankcase by the separator device to a predetermined amount, thereby preventing unwanted oil passage from the crankcase into the separator under conditions of large vacuum.
Although air-oil separator systems using such separate vacuum limiters or regulators have proven effective in separating and removing oil from crankcase air-oil mixtures, such systems depend on the gravity flow of collected oil from the separator through an oil drain line that is connected to an engine block. The oil drain line in such systems include a check valve disposed therein to prevent the unwanted passage of oil from the engine block and into the separator under conditions of excessive vacuum within the separator. The oil collected in the separator passes through the check valve after a sufficient pressure head of oil is built up in the drain line. Under conditions where the air filter is allowed to become excessively dirty, the vacuum generated by the separator can become great enough so that the pressure head of oil in the drain line is insufficient to permit oil passage to the engine block, thereby causing the oil level in the drain line to rise and interfere with the efficient separating operation of the system. Additionally the need to install and position of such separate vacuum limiter on or near and engine of a modern vehicle has become an increasing challenge due to spatial limitations in the engine compartment.
It is, therefore, desired that an air-oil separator device be constructed in a manner that provides both crankcase vacuum regulation and internal separator device vacuum regulation to enhance the efficient oil separating, collection, and removal operations of the device. It is desirable that the device be constructed in a manner that does so without requiring additional space within an engine compartment for mounting. It is also desired that the air-oil separator device be easy to install and use without a need for special equipment or instruction.